How to get the “Heart of Corruption” artifact?

Heart of Corruption - an artifact that Felicia has heard a lot about. Apparently, it allowed the possessor to gain certain demonic powers and influence his surroundings with demonic magic. Only how to get it if it was in Hell. Well, it may not have been the best solution, but choosing between looking for a way to get into Hell, trying to steal it, and making a pact with demons, she preferred the second option. In her life she has encountered many creatures, humans, mutants and.... just demons. She also knew one, a certain Mephisto. So it remained for her to make an appointment with a demon, offer him a deal while cheating him at the same time, fulfill the deal and gain the Heart of Corruption. Easy, right?

So she started with the simplest issue, making an appointment with him. She picked up the phone and texted him, "Hey, I have business. Would you like to meet and discuss it? How about tonight?" Easy. But before she had time to think about how to conduct the whole conversation she smelled sulfur and smoke. Guessing what it meant she got up from the couch and walked into the kitchen. Yes, Mephisto was already there, a suit-clad red-skinned demon.

“Well hey Mephisto, I thought we would arrange like civilized people for the evening.” - said Fel without showing fear

"People? Good for you." - he snorted somewhat amused - “What's the deal and you better not waste my time.”